Zhihong Zhuang; Yicheng Zhang; Liang Hu; Jianli Wang; Zhao Zhang; Weiqiang Han
Abstract
Silver (Ag) is a typical catalyst for CO2 electroreduction. To improve the CO faradaic efficiency, ZIF-8 supported thiol-capped Ag nanoparticles (Ag NPs) of about 3.9 nm were facilely synthesized by reducing Ag + in ZIF-8 suspension in the presence of thiol-containing mercaptopropionic acid (MPA) molecules. ...
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Silver (Ag) is a typical catalyst for CO2 electroreduction. To improve the CO faradaic efficiency, ZIF-8 supported thiol-capped Ag nanoparticles (Ag NPs) of about 3.9 nm were facilely synthesized by reducing Ag + in ZIF-8 suspension in the presence of thiol-containing mercaptopropionic acid (MPA) molecules. MPA can induce the monodisperse Ag NPs formation, cap on the surface of Ag NPs and immobilize on ZIF-8 through coordinating with the unsaturated Zn 2+ cations. The Ag/ZIF-8 can efficiently reduce CO2 to CO with a maximum CO faradaic efficiency of 92.3% at the potential of −0.88 V (vs. RHE), higher than that of ZIF-8 and Ag/C. The performance improvement in CO2 electroreduction over Ag/ZIF-8 is probably attributed to the small-size of Ag NPs and the synergistic effect between Ag NPs and ZIF-8.
Ranjana S. Varma; D.C. Kothari; A.K. Mallik; A. Bhatnagar; D. Kanjilal; S. Santra; R.G. Thomas; R. Tewari; S. Neogy; G.K. Dey
Abstract
Silver ion exchanges on silicate glasses were carried out at different temperatures 320 °C, 400 °C, and 500 °C for 60 min. The exchanged glasses were either annealed at 500 °C for 60 min or swift heavy ion (SHI) irradiated using 120 MeV Ag 9+ ions at a fluence of 5 x 10 12 ions/cm 2 . ...
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Silver ion exchanges on silicate glasses were carried out at different temperatures 320 °C, 400 °C, and 500 °C for 60 min. The exchanged glasses were either annealed at 500 °C for 60 min or swift heavy ion (SHI) irradiated using 120 MeV Ag 9+ ions at a fluence of 5 x 10 12 ions/cm 2 . Silver nanoparticles were formed in the samples ion exchanged at 500 °C without any post-exchange treatments. Post-exchange annealing treatment resulted in silver nanoparticle formation for samples ion exchanged at temperature of 320 °C and 400 °C. Whereas post irradiation treatment for ion exchanged sample at 320 °C resulted in Ag4 nanocluster formation. After post-irradiation, the density of Ag nanoparticles increases for the sample ion exchanged at temperature of 500 °C. RBS was used to obtain silver depth profiles in the ion exchanged samples. Near surface accumulation of Ag atoms is observed in the RBS spectra for the samples prepared at high ion exchange temperature of 500 °C or SHI irradiated samples, in which Ag nanoparticle formation was also observed. UV-vis absorption spectroscopy and Transmission Electron Microscopy (TEM) were used to obtain signatures of nano-particles and to estimate their size. The ion exchanged glasses without nanoparticles were characterized for their possible use in multimode planar waveguides. The post-exchange treated glasses lost their waveguide property, but exhibited nonlinear optical property indicating their potential use for optical switching. Open aperture z-scan measurements for the sample prepared at high ion exchange temperature of 500 °C shows optical limiting behavior, whereas the samples prepared at low ion exchange temperature followed by annealing or irradiation show saturation behavior.
Ranjana S. Varma; D.C. Kothari; S. Santra; R.G. Thomas; R. Tewari; S. Neogy; C.S. Suchand Sandeep; Reji Philip; D. Kanjilal
Abstract
In the present work, we have used swift heavy ions (SHI) irradiation and post irradiation annealing to synthesize Ag nanoparticles in fused silica. Fused silica samples deposited with 15 nm of Ag film were irradiated using SHI beam of 120 MeV Ag 9+ ions at different fluences and post irradiation annealing ...
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In the present work, we have used swift heavy ions (SHI) irradiation and post irradiation annealing to synthesize Ag nanoparticles in fused silica. Fused silica samples deposited with 15 nm of Ag film were irradiated using SHI beam of 120 MeV Ag 9+ ions at different fluences and post irradiation annealing was done at 500 °C in air for 30 min. The samples were characterized using UV-vis absorption spectroscopy, Rutherford Backscattering Spectrometry (RBS), GAXRD, Transmission Electron Microscopy (TEM), and open aperture z-scan measurements. The signature of Ag nanoparticles was observed in optical absorption spectra and the average size of the Ag nanoparticles was estimated using Mie’s theory. The size of the nanoparticles (~3 nm) was also confirmed from the GAXRD and TEM measurements. RBS results for Ag/SiO2 irradiated with the fluence of 5 x10 13 ions/cm 2 shows the decrease in slope at the interface of the Ag profile, indicating a partial mixing at a fluence of 5 x10 13 ions/cm 2 . Open aperture z-scan measurement of Ag/SiO2 SHI irradiated sample after annealing shows a saturation behavior, indicating that the sample is optically non-linear. The sample shows saturation behavior but does not show optical limiting behavior, which indicates that the size and number density of nanoparticles are low. The ability to control the particle size using ion beam technique as a function of fluence and observed nonlinearity results provide concrete evidence that Ag nano composite glasses can be used in nonlinear and optical limiting application.
Jyoti Rozra; Isha Saini; Sanjeev Aggarwal; Annu Sharma
Abstract
Structural and optical properties of Ag-glass nanocomposite, synthesized by the combined use of vacuum deposition method and subsequent thermal annealing have been studied using UV-Visible absorption spectroscopy, Field emission scanning electron microscopy (FE-SEM) along with Energy dispersive analysis ...
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Structural and optical properties of Ag-glass nanocomposite, synthesized by the combined use of vacuum deposition method and subsequent thermal annealing have been studied using UV-Visible absorption spectroscopy, Field emission scanning electron microscopy (FE-SEM) along with Energy dispersive analysis of X-rays (EDAX), Transmission electron microscopy (TEM) and Photoluminescence spectroscopy. Ag-glass nanocomposites were synthesized by depositing Ag on glass slides and the resulting samples were annealed at various temperatures from 300°C to 550°C for 1 hour. The fingerprint feature of Ag nanoparticles formation i.e. the surface plasmon resonance peak is observed around 427 nm in absorption spectra of Ag-glass samples annealed at various temperatures, this confirms the formation of Ag nanoparticles in glass. The size of Ag nanoparticles has been found to increase with increase in annealing temperature. At an annealing temperature of 400°C the size of Ag nanoparticles comes out to be 4.6 nm which increases to a value of 10.0 nm at an annealing temperature of 550°C. TEM micrograph further confirms the formation of Ag nanoparticles of size 8 + 2 nm at an annealing temperature of 550°C. Further, analysis of UV-Visible absorption and reflection data indicates towards the increase in refractive index of Ag nanoparticles doped glasses. It has been established that with the insertion of Ag nanoparticles of size 8 + 2 in glass the refractive index of the resulting nanocomposite increases to a value of 1.96. The dispersion parameters such as single-oscillator energy Eo, and the dispersion energy Ed have been discussed in terms of the Wemple-DiDomenico single-oscillator model. Photoluminescence spectra of silver glass nanocomposite have been studied and observed spectroscopic features have been correlated with various transitions of silver ions. Such studies are vital for designing optical materials for example optical communication, photonic devices etc.
Jai Prakash; A. Tripathi; G. B. V. S. Lakshmi; V. Rigato; Jalaj Tripathi; D. K. Avasthi
Abstract
Thin metal films of Ag (~10 nm) deposited on spin coated PVC film on quartz substrate, were irradiated with 150 keV Ar ions at fluences varying from 5×10 15 to 5×10 16 ions/cm 2 and characterized with Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM), scanning electron ...
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Thin metal films of Ag (~10 nm) deposited on spin coated PVC film on quartz substrate, were irradiated with 150 keV Ar ions at fluences varying from 5×10 15 to 5×10 16 ions/cm 2 and characterized with Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. RBS spectra show sputtering of the Ag film. As a result of ion irradiation, isolated Ag nanoparticles are formed on the surface. The size and size distribution of Ag nanoparticles are found to be dependent on ion fluence. Contact angle measurements were carried out to study the hydrophilic nature of the surface at varying fluences. Results are explained in the framework of sputtering from the surface due to dense collision cascade resulting from Ar ion and Ag/PVC film interaction.